832 research outputs found
Forensics and ship logs solve a 200-year mystery about where the first kiwi specimen was collected
The following article is republished from The Conversation, dated 14 April 2021 (https://theconversation.com/forensics-and-ship-logs-solve-a-200-year-mystery-about-where-the-first-kiwi-specimen-was-collected-158410).
As required in this journal’s republishing guidelines, the article has not been edited, but we have attributed the authors and their institute
Preliminary evaluation of human health risks from ingestion of organotin contamined seafood in Brazil
The unexpected survival of an ancient lineage of anseriform birds into the Neogene of Australia: the youngest record of Presbyornithidae
. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.Presbyornithids were the dominant birds in Palaeogene lacustrine assemblages, especially in the Northern Hemisphere, but are thought to have disappeared worldwide by the mid-Eocene. Now classified within Anseriformes (screamers, ducks, swans and geese), their relationships have long been obscured by their strange wader-like skeletal morphology. Reassessment of the late Oligocene South Australian material attributed to Wilaru tedfordi, long considered to be of a stone-curlew (Burhinidae, Charadriiformes), reveals that this taxon represents the first record of a presbyornithid in Australia. We also describe the larger Wilaru prideauxi sp. nov. from the early Miocene of South Australia, showing that presbyornithids survived in Australia at least until ca 22 Ma. Unlike on other continents, where presbyornithids were replaced by aquatic crown-group anatids (ducks, swans and geese), species of Wilaru lived alongside these waterfowl in Australia. The morphology of the tarsometatarsus of these species indicates that, contrary to other presbyornithids, they were predominantly terrestrial birds, which probably contributed to their long-term survival in Australia. The morphological similarity between species of Wilaru and the Eocene South American presbyornithid Telmabates antiquus supports our hypothesis of a Gondwanan radiation during the evolutionary history of the Presbyornithidae. Teviornis gobiensis from the Late Cretaceous of Mongolia is here also reassessed and confirmed as a presbyornithid. These findings underscore the temporal continuance of Australia’s vertebrates and provide a new context in which the phylogeny and evolutionary history of presbyornithids can be examined
Mycoplasma genitalium promotes epithelial crossing and peripheral blood mononuclear cell infection by HIV-1
Background Mycoplasma genitalium co-infection in HIV-infected individuals has been reported to increase the shedding of HIV in the urogenital region of females. To better understand this relationship, we investigated the influence of M. genitalium on the transmission and replication of HIV using an in vitro model. Methods The Transwell co-culture system was employed to assess the crossing of an endocervical cell barrier by HIV-1. Immunocytochemistry and confocal microscopy were used to assess the distribution of the nectin-1 molecule on M. genitalium -infected epithelial cells of the End1/E6E7 endocervical cell line, grown as monolayers in the insert wells. Peripheral blood mononuclear cells (PBMC) were cultured in the bottom wells to assess the effects of M. genitalium , passing through the semipermeable culturing membrane, on subsequent HIV infection of susceptible target cells. Results Infection of the endocervical cells with the adhesion-positive M. genitalium G37 strain (wild-type) significantly elevated the passage of HIV across the epithelial cell barrier relative to HIV transfer across endocervical cells infected with the adhesion-negative M. genitalium JB1 strain. Immunostaining of the M. genitalium -G37-infected epithelial cells disclosed capping and internalization of the junctional regulatory protein nectin-1, in association with reduced transepithelial resistance (TER) in the cell monolayer. When PBMC were cultured beneath insert wells containing M. genitalium -G37-infected epithelial cell monolayers, we observed significantly enhanced infectivity and replication of HIV added afterward to the cultures. Conclusions M. genitalium influences events on both sides of a cultured mucosal epithelial monolayer: (1) by infecting the epithelial cells and reducing the integrity of the barrier itself, and (2) by activating HIV target cells below it, thereby promoting HIV infection and progeny virus production
Universal 1/f Noise from Dissipative SOC Models
We introduce a model able to reproduce the main features of 1/f noise:
hyper-universality (the power-law exponents are independent on the dimension of
the system; we show here results in d=1,2) and apparent lack of a low-frequency
cutoff in the power spectrum. Essential ingredients of this model are an
activation-deactivation process and dissipation.Comment: 3 Latex pages, 2 eps Figure
ESTUDO DAS TENDÊNCIAS DO TOTAL DE PRECIPITAÇÃO E DO NÚMERO DE DIAS PARA EVENTOS EXTREMOS NO LITORAL NORTE, SP
Eventos extremos de chuvas podem tornar-se mais frequentes, aumentando a possibilidade de desastres naturais, tais como grandes inundações e deslizamento de solos. O interesse da sociedade ocorre devido às possíveis perdas materiais e humanas. Assim, as tendências anual e sazonal do número de dias chuvosos e total de precipitação foram estudadas para vários limiares de taxas diárias de precipitação extrema no Litoral Norte de São Paulo. De acordo com o número de dias de chuva, observou-se que houve um aumento de eventos com taxas maiores ou iguais a 50 mm/dia. Para as taxas maiores que 25,4 mm/dia, houve um provável aumento significativo de ambas as tendências para Maresias/SS, Caraguatatuba e Picinguaba/U para o ano, verão e primavera. De acordo com o número de dias chuvosos, observou-se que houve um aumento provável da tendência em Caraguatatuba para taxas maiores ou iguais a 50 mm/dia no ano e outono. Picinguaba/U apresentou provável aumento significante das tendências no inverno e ano. No verão, não houve nenhum caso de tendência significante para 25,4 mm/dia; aumentou significantemente provável em Picinguaba/U e Caraguatatuba para total de precipitação para 50 mm/dia e para ambas as variáveis em Mato Dentro/U, Caraguatatuba e São Francisco/SS para 75 mm/di
On the taxonomic composition and phylogenetic affinities of the recently proposed clade Vegaviidae Agnolín et al., 2017 ‒ neornithine birds from the Upper Cretaceous of the Southern Hemisphere
© 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/
This author accepted manuscript is made available following 24 month embargo from date of publication (Feb 2018) in accordance with the publisher’s archiving policyPolarornis and Vegavis from the Upper Cretaceous of Antarctica are among the few Mesozoic birds from the Southern Hemisphere. In the original descriptions, they were assigned to two widely disparate avian clades, that is, Gaviiformes and crown group Anseriformes, respectively. In a recent publication, however, specimens referred to both taxa were classified into a new higher-level taxon, Vegaviidae, to which various other late Mesozoic and early Cenozoic avian taxa were also assigned. Here, we detail that classification into Vegaviidae is poorly supported for most of these latter fossils, which is particularly true for Australornis lovei and an unnamed phaethontiform fossil from the Waipara Greensand in New Zealand. Plesiomorphic traits of the pterygoid and the mandible clearly show that Vegavis is not a representative of crown group Anseriformes, and we furthermore point out that even anseriform or galloanserine affinities of Vegaviidae have not been firmly established
The Rayleigh-Schr\"odinger perturbation series of quasi-degenerate systems
We present the first representation of the general term of the
Rayleigh-Schr\"odinger series for quasidegenerate systems. Each term of the
series is represented by a tree and there is a straightforward relation between
the tree and the analytical expression of the corresponding term. The
combinatorial and graphical techniques used in the proof of the series
expansion allow us to derive various resummation formulas of the series. The
relation with several combinatorial objects used for special cases (degenerate
or non-degenerate systems) is established.Comment: 16 pages, 3 figure
Noise Probe of the Dynamic Phase Separation in La2/3Ca1/3MnO3
Giant Random Telegraph Noise (RTN) in the resistance fluctuation of a
macroscopic film of perovskite-type manganese oxide La2/3Ca1/3MnO3 has been
observed at various temperatures ranging from 4K to 170K, well below the Curie
temperature (TC = 210K). The amplitudes of the two-level-fluctuations (TLF)
vary from 0.01% to 0.2%. We use a statistical analysis of the life-times of the
TLF to gain insight into the microscopic electronic and magnetic state of this
manganite. At low temperature (below 30K) The TLF is well described by a
thermally activated two-level model. An estimate of the energy difference
between the two states is inferred. At higher temperature (between 60K and
170K) we observed critical effects of the temperature on the life-times of the
TLF. We discuss this peculiar temperature dependence in terms of a sharp change
in the free energy functional of the fluctuators. We attribute the origin of
the RTN to be a dynamic mixed-phase percolative conduction process, where
manganese clusters switch back and forth between two phases that differ in
their conductivity and magnetization.Comment: 15 pages, PDF only, Phys. Rev. Lett. (in press
Polyendocrinopathy in Children, Adolescents, and Young Adults With Type 1 Diabetes: A multicenter analysis of 28,671 patients from the German/Austrian DPV-Wiss database
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